Automatic telephone system



C. L. GOODRUM.

Patented J ully 8, 1919.

2 sH'l-:ETs-SHEET1.

k l@ lk m .s \I

[har/es L 600 drum.

C. L. GobnRun/x.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION F'ILED JULY 28.1911.

Patented July 8, 1919. I

2 SHEETS-SHEET 2.

.,m. f* Mm Hd 0 W@ ML. S k W C UNITED. sTATEs PATENT oErroE.-

CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application filed July 28, 1917.

To all whom it may concern Be it known that I, CHARLES L. GOODRUM, acitizen of the United States, residing at New York, in the county of NewYork and lState of New York, 'have invented certain 'count of theirknowing that it is impossible for the called party to nd out who iscalling. It is, therefore, the object of this invention to provide meanswhereby a called subscriber can lock up the series of switches used tocomplete the connection from a calling line to his line, and also tocause an alarm to operate at the central oice to notify an attendantthereat t0l trace the connection and determine the line lupon which thecall originated. p

In accordance ,with this object, a diii'erenti-al relay is provided inthe battery supply circuit of the connector switches, and a push buttonis provided at each subscribers substation. When this ibutton is pressedat a called substation, one winding of the differential relay of theconnector switch connected thereto, is shunted, thereby causing therelay to become energized and attract its armature which is mechanicallylocked up. The attraction of the armature permanently opens 'the releasecircuit of switches used in completing 'the connection, and therebyprevents the release of these `switches when either subscriber hangsV up45-V hisreceiver. The attraction of the armature of the differentialrelay also causes an alarm to operate at the central office. This alarmnotifies an attendant at the central office that a called lparty haslocked up a series of switches and that he must trace out the connectionand determine the line upon which the call originated.

It is believed that the invention will best be understood by tracing acall from a call- Specication of Letters Patent.

Patented July s, 1919.

Serial No. 183,295.

ing subscribe-r to a called subscriber, reference being had to theaccompanying drawings, in which Figure 1 diagrammatically shows acalling substation, a line finder switch and a first selector switch;and Fig. 2 diagrammatically shows a connector switch and a calledsubstation.

When the subscriber at substation A removes his receiver from the hook,a circuit is completed from grounded battery, left-hand winding of relay1, outer armature and back contact of relay '2, telephone apparatus atsubstation A, sender S, back contact and inner armature of relay 2,right-hand winding of relay 1 to ground. Relay 1, 'by attracting itsarmature, completes a circuit from grounded battery, left-hand windingof relay 1, outer armature and back contact of relay 2, conductor 3,armature andv front Contact of relay 1, contact spring 70, back contactand left-hand armature of relay 4, winding of relay 5 to ground. Relay5, by attracting its left-hand armature, completes a locking circuit foritself which is independent of the armature and back contact of relay 4.Relay 5, by attracting its right-hand armature, completes a circuit fromgrounded battery, winding of relay 6, right-hand armature and frontcontact of relay 5 to ground. Relay 6 at its right-hand armature andfront contact, completes a circuit from grounded battery, winding ofrelay 4, right-hand armature and front Contact of relay 6 to ground.Relay 4 `becomes energized and by attracting its right-hand armaturemaintains the release circuit of the line finder open during theoperation of the line finden Relay 6 at its left-hand armature and frontcontact, completes a circuit from grounded battery, winding of primarymagnet 7, sideswitch arm 8, back contact and armatureof secondary magnet9, armature and back contact of primary magnet 7, right-hand armatureand back4 contact of release magnet 11,

` ing subscribers line. When the arm 14 engages tliis contact 15,`gr0undwill be found thereon, which Completes the following cir1 v cuit-fromgrounded battery, winding of primaintained energized by the currentflowing through this circult, thereby preventing further stepping of theswitch. The escape magnet 10 is also energized by the current flowingthrough this circuit and upon its energization moves the side-switcharms into their Isecond position.

In position 2primary magnet 7 and the escape magnet 10 are maintainedenergized over the following circuit, from `grounded battery, winding ofprimary magnet 7 Winding of escape magnet 10, side-switch arm 13,vside-switch arm 12. left-hand armature and front contact of relay6,right-hand armature andfront contact of relay 5 to ground. 3A steppingcircuit is now closed for the secondary magnet 9 from grounded battery,winding of secondary magnet 9, side-switch arm 8, back contact andarmature of secondary magnet 9,.righthand armature and front contact ofescape magnet 10, right-hand armature and back contact of release magnet11, side-switch arm 12, lefthand armature and front contact of relay 6,right-hand armature and front contact of relay 5 to round. Thissteppingcircuit for the secondary magnet 9 is maintained until thebrushes 16, 17'and 18 of the line finder engage the terminals 19, 20 and21; of the calling line, at which timev a circuit 1 s completed fromgrounded battery, winding of the cut-olf relay 2, terminal 19, brush1.6, contact sprin 23, left-hand armature and front contact o escapemagnet 10, resistance 22, side-switch arm 12, left-hand varmature andfront contact of relay 6, right-hand armature and front contact of relay5 -to ground. ,Rela hoylding circuit of relay 5,. Relay 5 becomesdenergized and opens the circuit of escapey magnet 10, which denerg'izesand moves the side-switch arms into their third jposition'. Relay 2 isstill maintained energized in position 3y over a circuitffrom groundedbattery, winding of relay 2, lterminal 19, brush 16, contact spring 23,make-before-break contact 7 left-hand armature and back' contact ofreleasev magnet 11- to ground. As soon as the side-switch arms 24 and 25move into their third position, the circuit is completed for line relay26 of the first selector switch from grounded battery, left-hand windingof relay 26, side-switch arms 27 and 25, brush 17 terminal 20, telephoneapparatus at substation A, sender S, terminal 21, brush 18, side-switcharms 24 and 23, righthand winding of relay 26 to ground. Line relay 26by attracting its armature, completes a circuit from grounded battery,winding of relay 29, front contact'and armal2 by attracting itsarmatures, opens they series of impulses. In response to each impulsetransmitted,l the line relay 26 is mo- @mentar'ily denergized, therebyclosing the circuit from grounded battery, Winding ofl prlmary magnet31, secondary ofi-normal contact 32, front contact and'armature of relay29, back contact and armature of relay 26 yto ground. A circuit is alsocompleted in parallel with primary magnet 31 from l grounded battery,winding of relay 30, front contact and armature of relay 29, armatureand back contact of relay 26 to ground. The energization of relay' 30completes the circuit 'rom grounded battery, winding of escape magnet33, side-switch arm 36, armature and front contact of relay 30 toground. Relays 29 and 30 are arranged to maintain their armaturesattracted during the transmission of the impulses. At the end ofthefirst series of impulses the line relay -26 remains energized for asuficient length of time to cause the denergization of relay 30,

which in turn causes the denergization of escape magnet 33` t0 move theside-switch arms into their second position.

In -position 2 a stepping circuit isclosed for the secondary magnet 34from grounded battery winding'of secondary magnet 34,

armature and back contactof this magnet, side-switch arm 35, frontcontact and armature of relay 26 to ground. Each energization of thesecondary magnet 34 moves the brushes 38, 39 and 40 of the selectorswitch .into engagement with the terminals of a trunk in the selectedgroup. As long as busy trunks are engaged by the brush 38, no

potential will be found upon the terminal 41,

but as soon as the terminals of an idle trunk.

are engaged, ground will be found upon the test terminal 41, therebycompleting a circuit from grounded battery, winding of escape magnet 33,side-switch arm 36, brush 38, terminal 41 to ground at the idleconnectorswitch. Escape magnet 33 becomes energized and moves thesideswitch arms into their third position.-

Side-switch arms 27 and 28by 'movingv into l'their third position extendthe calling line through to the connector switch. A circuit is thencompleted from grounded battery, right-hand winding of line rel-ay '44,

terminal 42, brush 39, side-'switch yarms 27' and 25, brush 17 terminal20, telephone apparatus at substation'A, sender S, terminal 2l, brush18, side-.switch arms 24 and 28,

brush 40, terminal 43, left-hand winding of line relay 44 to ground. Theenergization of relay 44 completes ai circuit from grounded battery,winding of relay 45, armature and front contact of relay 44. backcontact and armature of diiierential relay 62 to ground. The apparatus.is now in condition for the second series of impulses.

In response to each impulse of this series the line relay 44 ismomentarily denernet 47, side-switch arm 48, front contact andAright-hand armature of relay 45, back contact and armature of relay 44,back contact and armature of differential relay 62 to ground. A circuitis also completed for relay 46 in parallel with primary magnet 4.7.Relays 45 and 46 are arranged to maintain their armatures attractedduring the transmission of the impulses. The energization of relay 46completes a circuit from ground-y ed battery, front contact andright-hand armature of relay 46, winding of escape magnet 49, backcontact and armature of relayl `to ground. At the end of the sec- ;"bndseries of impulses, line relay 44 is maintained energized, therebycausing the deenergization of relay 46. Relay 46-by retracting itsright-hand armature opens the circuit of escape magnet 49 whichdenergizes and moves the side-switch arms into their second position.

In response to the third series of impulses the line relay 44 will bemomentarily denergized in the same manner as above, causing thefollowing circuit to be completed from grounded battery, winding ofsecondary magnet 50, side-switch arm 48, front contact and right-handarmature of relay 45, back Contact and armature of relay 44, backcontact and armature of differential relay 62 to ground. A circuit isalso completed for relay 46 in parallel with the secondary magnet 50.Relay 46 by attracting its righthand armature again completes vtheenergizing circuit of escape magnet 49 in the manner above described. Atthe end of the third series of impulses the line relay 44 is maintainedenergized, thereby causing the deenergization of relay 46. In responseto the second series of impulses, brushes 55, 56 vand 57 are moved intooperative relation with the terminals of the group of lines containingthe called subscriber. In response to the third series of impulses thebrushes 55, 56 and 57 are moved into engagement with the terminals ofthe line extending to the called substation. We will first assume thatthe called line is busy and, therefore. ground will be found upon thetest terminal 58. If this line is busy as a called line, this groundwill be connected through side-switch arm 52 and brush 55 of theconnector switch connected thereto, or if busy as a calling line, groundwill be connected through the lefthand armature and back contact ofrelease magnet. 11. malte-before-break contact 71, contact spring 23 andbrush 16 of the line finder connected thereto. Therefore, when relay 46denergizes after the third series of impulses. a circuit will becompleted for release magnet 68. provided thc called line is busy, thiscircuit being traced from grounded battery, winding of release magnet68, right-hand armature and back contact of relay 61, off-normal contact67, lefthand armature and back Contact of relay 46, side-switch arm 52,brush l55, terminal 58 to ground. Release magnet completes a .lockingcircuit for itself from grounded battery, winding of release magnet 68,lefthand armature and front contact of this magnet, off-normal contact81 to ground. Since the escape magnet 49 is made slow to retract itsarmatures, the circuit for the release magnet 68 will be closed beforethe side-switch armatures move into their third position. Theenergization of the release magnet 68 removes the holding pawls of theconnector switch in the well known manner, thereby causing the switch toreturn to its normal position. The release magnet 68 at its right-handarmature and front con tact connects the busy tone apparatus 8O to thelower line conductor, thereby notifying the calling subscriber that thecalled line is busy. The release magnet 68 at its lefthandarmature andfront contact completes the circuit of the release magnet 1'1 of the lmefinder switch from grounded battery, winding of the release magnet 11,primary off-normal contact 74, right-hand armature and back Contact ofrelay 4, side-switch arm 87, brush 33, terminal 41, conductor 76,lefthand armature and front contact of relay 45, front contact andleft-hand armature of release magnet 68, oii"normal contact, 81 toground. A circuit is also completed in parallel with magnet l1 fromgrounded battery, winding of the 4release magnet 72 of the firstselector switch and primary offnormal contact 73, The release magnets 11and 72 become energized and return the line finder and the firstselector respectively to their normal positions in the well-knownmanner.

,lf the called line had been idle at the time the brush 55 engaged theterminal 58, no ground would have been found thereon, so that thedenergization of relay 46 would have caused the denergization of escapemagnet 49 and the side-switch arms would have been moved into position3.

In position 3 a. circuit is 'completed from grounded battery, Winding ofrelay 46, side- 'switch arm 48, front contact and armature of relay 44,back contact and armature of differential relay 62 to ground. Relay 46becomes energized and again completes the energizing circuit of escapemagnet 49. Escape magnet 49 by attracting its armature completes acircuit from ringing generator (not shown), front contact. and armatureof escape magnet 49, winding of marginal relay 51, side-switch arm 53,brush 56, terminal 59, telephone apparatus at substation B, sender S.terminal 60, brush 57,"s1de-switch arm 54, front contact and armature ofrelay 44 to ground. The current flowing through this circuit is no-tsuflicient to operate marginal relayfl at this time, but as soon as thesubscriber at substation B removes his receiver from the hook, therebyshunting the -ringer at his substation, sufficient current Hows throughthe marginal-relay 51 to cause it tol,rattract its armature and open thecircuit of the escape magnet 49. Theescape magnet 49 -denergizes andmoves lthe sideswitch arms into their fourth position.

rIhe subscribers are now connected for conversation, current beingsupplied to the -called subscribers line from grounded battery,left-hand winding of relay 61, lefthand winding of dierential relay l62,sideswitch arm 53, brush 56 terminal 59, tele-` phone apparatus atsubstation B, sender SQ v.terminal 60, brush 57, side-switch arm 54,4

.tion of relay 44 causes in turn the ,denergization/ of relay 45. Groundis then conf nected to the release conductor 76 through p over thisconductor.

armature and back contact Aof differential relay 62, amature and backcontact of relay 44, right-hand armature and back contact of relay 45and left-hand armature and back contact of relay 61. Circuits are thencompleted for release magnets 11, 72 and 68 It will be seen that afterconnecti-o-n is once established the release of the switches used incompleting the connection is'controlled at the armature and back contactof the differential relay 62. If,

however, the called party wishes to find out who is talking to him, hepresses the key K1 before the calling party hangs up. The pressing ofthis key connects ground directly to the left-hand winding of thedifferentia-l relay 62. This shunts the righthand winding of the relayand causes it to attract its armature. Thearmature is mechanicallylocked up in its attracted position by the catch 63. The engagement ofthe arma.- ture of relay 62 with the catch 63 completes a circuit fromgrounded battery, winding of the relay 65, lamp 64, catch 63, armatureof relay 62 to ground. The current flowing through the circuit energizesthe relay 65 and lights the lamp 64. Relay 65 by attracting its armaturecompletes acircuit for the Ibuzzer 66 fro-m grounded battery, windingand armature and back contact of buzzer 66, armature and front contactof relay 65 to ground.` The attendant at the central office hearing thisbuzzer, is informed that a certain series of switches has been locked.

up, and seeing the light 64 which is indi-m vidual to a particularconnector, knows that that particular connector and the switchesconnectedthereto are the ones that should be traced to find out uponwhat line the call originated. The attraction ofthe armature ofrelay 62remo-ves ground from the release conductor 7 6 and thereby prevents therelease of any of the switches when the called and calling parties hangup their receivers.

-What is claimed is: V

1. In -a telephonesystem, a calling subscribers line, a calledsu'bscribers line, autof matic switches, means for operating saidswitches to complete a connectionv between said subscribers lines,releasing means for said switches normally under'the control of saidsubscribers, and means under the control of the called subscriber forremoving the control of said releasing means from both of saidsubscribers.

2. In a telephone system, a calling subscribers line, a calledsubscribers line, automatic switches, means for operating said switchesto complete a connection between said subscribers/lines, a releasemagnet for each switch,Y circuits for` saidrelease magnets normallyunder the control of said subscribers, and means under the control ofthe called subscriber forpermanently opening said release circuitstoremove the control of said circuits from both'of said subscribers..

3. In a telephone system, a calling subscribers line, a calledsubscribers line, automatic switches including a connector switch, meansfor operating said switches to complete a connection betweensaidsubscribers lines, a differential relay at said connector switch,` avrelease magnet for each of said switches, circuits for said releasemagnets controlled by said differential relay, and means under thecontrol of the called subscriber for operating said relay to preventtheoperation of any of said release magnets by either of saidsubscribers.

controlled by said differential relay, and" means under the control ofsaid called sub1 scriber for shunting one winding of said relay to causether operation thereof to prevent the operation of any of said releasemagnets by either of said subscribers.

5. AIna telephone system, a calling subscribers line, a calledsubscribers line, automatic switches including a connector switch, meansfor operating said switches tocomplete a connection between saidsubscribers lines, a differential relay at said connector switch, arelease magnet for each of said switches, circuits forsaid releasemagnets controlled by said differential relay. a mamially operabledevice at the called subscribers substation, and means operated inresponse to the operation of said device by the called subscriber forshunting one winding of said relay to cause the operation thereof toprevent the release of any of said switches of either of saidsubscribers.

6. In a telephone system, a calling sub,- scribers line, a calledsubscribers line, a central office, automatic switches thereat.` meansfor operating said switches to complete a connectionbetween said'.subscribers lines, a releasing means for said switches normally underthe control of said subscribers, an attendants position at said centraloffice, a signal at said position, and means under the control of the-called subscriber for removing said releasing means from under thecontrol of said-subscri'bers, and for operating said signal at saidposition to notify the attendant t0 ascertain the calling s-u'bscribersline, for the called subscriber.

7. In a. telephone system, a calling subscribers line, a calledsubseribers line, a central ofiice, automatic switches tliereat, meansfor operating said switches to complete a connection between saidsubscribers lilies, a release magnet for each switch, circuits for saidrelease magnets normally under the cont'rol of said subscribers, anattendants position at said central office, a signal at said position,and means under the control of the called subscriber for permanentlyopening said release circuits to remove said release magnets from underthe control of said subscribers, and for closing a circuit for saidsignal to notify the attendant to ascertain the calling subscribers linefor the called subscriber.

8. .In a telephone system, a calling line, a

called line, a central office, automatic switches including a connectorswitch at said office, means for operating said switches to complete aconnection between said lines, a differential relay at said connectorswitch, releasing means forsaid switches cont-rolled by said relay, anattendants position at said office, a signal at said position, andmanually operable means at the called partys substation for causing saidrelay to operate to prevent the operation of said releasing means byeither of said parties and to cause said signal to operate to notify theattendant to ascertain the calling line for the called Party;

9. In a telephone exchange system, a central oflice, a signal thereat,calling and called subscribers lines terminating at said central ofiice.automatic switches for interconnecting said lines, means under thelcontrol of the called subscriber for locking said switches in anactuated condition to mainl1. In a telephone exchange system, callingand called subscribers lines, automatic switches for interconnectingsaid lines, meansfor releasing said automatic switches, andelectromagnetic means under the exclusive control of the calledsubscriber for preventing the operation of said releasing means.

12. In a telephone exchange system, calling and called subscriberslines, automatic switches forv interconnecting said lines, means forreleasing said automatic switches, and means operable at will by thecalled subscriber exclusively for preventing the operation of saidreleasing means.

13. In a telephone exchange system, subscribers lines, automaticswitches for interconnecting said lines, means for releasing saidautomatic switches, a differential relay for controlling said releasingmeans, and means under the exclusive control ofthe called subscriber forcausing said differential relay to prevent the operation of saidreleasing means.

7114.- In a telephone exchange system, subscribers lines, automaticswitches for. inter .connecting said lines, means for releasing saidautomatic switches, a differential relay for controlling said releasingmeans, and means operable at will by the called subscriber exclusivelyfor causing-the differential relay to Vprevent the operation of saidreleasing means.

15. In a telephone exchange system, subscribers lines, automaticswitches for interconnecting said lines, a differential relay, a circuitfor releasing said switches including the armature of said differentialrelay when both of its coils are energized, and means operable at willfor shunting one winding of said differential relay and thereby breakingthe circuit for releasing the automatic switches.

16.111 a telephone exchange system, subscribers lines, automaticswitches for interconnecting said lines, a differential relay, a circuitfor releasing said switches including the armature of said differentialrelay when both of its coils are energized, and means under control ofthe called subscriber for shunting one winding of said differentialrelay thereby breaking the circuit for releaslay, and means under thecontrol of the called subscriber for operating said relay to preventtheoperation of any of .said release magnets by either of said subscribers.

18. In a telephone system, a calling line, a called lline, a centraloiice, automatic 'switches at said office, means for operating saidswitches to complete a connection between said l1nes, a dilerentialrelay, releasing means for said switches controlled bysaid relay, anattendants position at said oiice, a si al at said position, andmanuallyv opera le means at the called partys substation for causingsaid relay to operate' to prevent the operation of 'said releasing I vmeans by either of said parties to cause said signal to notify` theattendant to ascertain the calling line for the called party.

191 In a telephone exchange'system, subscribers lines, automaticswitches for interconnecting said lines, a differential relay, a'

circuit for releasing said switches including the armature ofsaiddii'erential-relaywhen both of its coils arev energized', and meansoperable by the called 'subscriber for 'shunting-one. winding of saiddifferential relay and causing said relay to attract its armature andthereby breaking the circuit for re. I

leasing the automatic switches, and*- means for latching the armatureofsaid 'relay in its attracted osition. 20. In a te ephone exchange"system, "sub: scribers lines, automatic Iswitches'forinterconnectingsaid lines, a central oilice, a'sig-'f nal thereat, a differentialrelay, av circuit for the called subscriber .for shunting one winding'of said differential relay and thereby vreleasing said switchesincluding the arma- `ture of said diiferential relay when vboth of. itscoils are energized, means operable by*r causing said relay to attractits armature for breaking the circuit .for releasing the automaticswitches, a latch for retaining the armature loi the differential relayin its attracted position, and a circuit established throughsaidarmature and latch for ,operating saidy signal at the central ofiice.

In witness whereof I hereuntosubscribe my name this 21st day of July, A.D. 1917.

, CHARLES L. GOODRUM.

